The TD-SCDMA system is a time division synchronous code division multiple access system, wherein the synchronization requires that the time that the uplink signals of all activated user apparatuses working at the same time slot in a cell reach the base station of the cell are generally the same, thus the interference between adjacent time slots can be reduced, and a relatively high signal-to-noise ratio can be kept when a digital receiver conducts sampling.
However, in the actual TD-SCDMA system, even a synchronization control algorithm is used, the time that the signals from all user equipments to the base station cannot be completely the same, but the purpose of reducing the interferences between adjacent time slots can be achieved as long as the differences between the times that the signals from all the user equipments to the base station are controlled within an allowable range (such as the width of several chips). But this can not guarantee that a digital receiver, when conduct sampling, can keep a relatively big signal-to-noise ratio, because a tiny difference (such as within the width of one chip) between the time that the signals from all the user equipments to the base station can greatly reduce the signal-to-noise ratio at the time that the digital receiver conducts sampling, thereby reducing the performance of the whole system.